Essays in Applied Economics

In this work we analyze the impact of high-speed rail (HSR) connection on regional innovation performance in Italy. By using a balanced panel of 89 NUTS-3 regions observed over the period 1980–2019, we conduct a causal analysis that exploits the staggered opening of HSR stations in a extended two-way fixed effects (ETWFE) Difference in Differences (DiD) design. We find that HSR access increases both the quality and the quantity of innovation, raising per-capita forward-citation–weighted patents by 27% to 39%, with effects that persist over time. Moreover, estimates of a dyadic gravity model show that HSR boosts inter-regional inventor collaboration by about 30%, suggesting reduced effective distance as a key mechanism for improved innovative performance, while a social network analysis (SNA) reveals an increase in the degree of centrality in the regional innovation network associated to better HSR access. Sectoral results point to especially strong responses in chemistry, electrical and mechanical engineering and in in less-accessible, Centre-Southern, and initially less innovative regions.